class Node:
sef_ init__ (self,)
self.value=value
self.next=None
class List:
def_ init__ (self):
self . head=Node(-1)
def insert_ before(self ,date):
for i in date:
node=Node(i)
if self. head .next is None:
self . head. next=node
else:
node next=self head next
self .head. next=nodecur . next=cur . next . next
def list_ element_ add(self,i,value):
break
nodenode. next
if node is Node :
return False
#第i个结点前插入值为value的结点
node_ new=Node(value #éJtàJ gindex=0
node=self . head. next
while node: #*I n
index= index+1
if index==i-1 :
node_ new . next=node . next#jARnode . next=node_ new